Weird Rail Pressure Issue (altitude or heat related)

[jambbii]

Truck is an 06. Smarty udc, bw363, fass150 and 60%. 130k on the truck.


I am stumped guys... This has happened twice while towing. Rail pressure spikes and stays at 26k basically over 1800rpm. It seems like the only actually regulating RP is engine speed. At idle it would go back to normal but would take some time to "bleed off". It seems like the FCA is just open.

First time this happened it was 118 out and I was heading up north camping hauling about 5k. Truck was running about 215. I was climbing a pretty steep grade and the truck just lurched forward like I just gained 50 hp. I was able to nurse it to the camping spot. The problem seemed to go away until the truck warmed up. We were at 7k feet elevation. Picked up an FCA and it did nothing. My neighbor brought a new RP sensor up as well as my programmer. The RP sensor did nothing. Reprogrammed the truck to stock and the problem disappeared.

Truck made it home no problems. Put my tune back on it and drove around for 2 months with no issues. It is still hot but has not run 215 since. I cleaned all the connections and put dielectric grease on them.

Last weekend we head up again with little more weight and same crap happens again (still pretty toasty in Az). Put the truck to stock and it made it up fine.... just slower. None of this makes any sense to me unless the smarty is doing something crazy but I don't understand how heat or altitude could affect programming.

Any help would be appreciated.

Josh

[crpower]

If you can log actual vs desired rp that might help.


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[jambbii]

Originally Posted by crpower

If you can log actual vs desired rp that might help.


Sent from my iPhone using Tapatalk

I can tell you it is way off. The way it ramps up is a direct correlations to engine speed (when it is freaking out). I have it programmed to max out at 24k under high load. I can hit 26k in park revving with no load. It feels to me like there like the fca is stuck open.... if that makes sense.

[apples24v]

did you ever figure this out?

[jambbii]

Originally Posted by apples24v

did you ever figure this out?

Nope. It has to be something related to the smarty but I have yet to duplicate anything. I have towed plenty of times but just hauling stuff around town. Won't be hauling the camper until it warms up again....